The present invention relates to a developing method and apparatus for developing only a desired area with a dry developer, more particularly to, a developing method and apparatus for developing a desired area of an electrostatic latent image bearing member by applying a dry developer only to a desired area of a developer carrying member at a desired time. Further, the present invention relates to a developing method and apparatus for multi-color developing the latent image on the image bearing member in accordance with the above developing and method.
Heretofore, it has been very difficult to develop, with a dry developer, only a desired part of a latent image on an image bearing member. For example, it is thought that a developer coating area of a two component developer layer on a developing roller is controlled by a mechanical shutter or the like, but the control area is different from that desired, because the two component developer layer formed in the conventional two component developer apparatus is thick. When the two component developer layer thus defined is contacted to a latent image bearing member, the development area further expands unclearly, so that it has been almost impossible to develop only a desired area of a latent image area.
Some proposals have been made as to a method of obtaining a multi-color recording by only one transferring step in an electrophotographic apparatus. However, those are all directed to a two color recording method wherein a positive latent image and a negative latent image are formed on an image bearing member, so that the latent image formation is not stable. In addition, it is required to use a reverse development. Therefore, those methods are not practical. Furthermore, there is another problem that the recording is not possible for more than two colors.